Combustion engine



Oct. 29, 1935. SASS AL I 2,019,321

COMBUSTION ENGINE Filed May 11, 1934 I 5& 54 4/ 5a '5 40 g 39 /0 45 Fig.3. 27 9 4s 38 M I l 560 480" '600" 220"; v zzz 12 w 1 Inventors; Friedrich Sass, Ernst Daiber,

Attorneg,

Patented Get.

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CDWUSTIQN mGfl Friedrich Sass, Berlin, and Ernst Daiber, Llchterfelde-West, Germany, assignors to General Electric Company, a corporation of New York Application May 11, 1934., Serial No. 325,024 In Germany .luly 12, 1933 3Claims.

The present invention relates to combustion engines, especially to engines of the Diesel type with airless fuel injection comprising a plurality of cylinders to which fuel is supplied. by means of fuel feeders actuated by the pressure within the cylinders. The feeders receive-the fuel by pumping means which may be a single pump or preferably a pump for each cylinder.

Difliculties are experienced with such engines when fuel is supplied simultaneously during a certain period of a cycle to all feeders because due to the simultaneous supply of fuel to all feeders the fuel supply to one or more of the feeders takes place during the period of the compression stroke in the cylinder, that is, when the fuel feeder is'subjected to a high pressure. The pump or pumps supplying fuel to such feeder or feeders would have to overcome the pressure on the feeder by the corresponding cylinder. This drawback could be overcome by the provision of special pumping means, for example, stronger pumps with respect to those cylinders in which the fuel supply to the corresponding fuel feeders takes place during a period of gh pres= sure within said cylinders.

The object of our invention is to provide an improved construction and arrangement for combustion engines of the type specified above whereby like pumping means for all cylinders may be operated simultaneously. This is accomplished in accordance with our invention by the provision of special storing devices connected between the pumping means and the feeders of those cylinders in which high pressure emsts during the compression stroke of the pump means.

For a better understanding of what we consider to be novel and our invention, attention is directed to the following description and the claims appended thereto in connection with the accompanying drawing which forms a part of our specification.

In the drawing, Figs.) and 1a are diagrammatic illustrations of combustion engines embodying our invention; Fig. 2 is a diagram illustrating the operation of a combustion engine of the type referred to above; and Fig. 3 is a somewhat diagrammatic view showing more in detail the arrangement according to our invention.

The combustion engine in Fig. 1 comprises six cylinders I, H, III, IV, V and VI. Fuel is supplied to the cylinders by pumping means including a fuel pump it for each cylinder. All six fuel pumps are driven by a common drive means i i which may be an eccentric or a cam on the crank shaft of the engine. Gonnected between each cylinder and the pumps Ill are fuel feeders 82 connected to the cylinders by conduits 25. In accordance with our invention we provide in the present example between the pumps l8 and the fuel feeders 12 of the cylinders I and III storing devices 5 B which will be described fulLv hereinafter. The storing devices is are connected to the pumps by conduits 5d and to the fuel feeders by conduits 55.

Fig. 1a illustrates a similar arrangement as m that of Fig. 1. Like parts in Fig. la therefore are designated by like reference characters primed. The only distinction between the arrangements of Figs. 1 and 1c is that whereas the the arrangement of Fig. 1 includes a separate fuel 15 pump at for each cylinder, the arrangement ac cording to Fig. 1a includes a pump it for compressing fuel for more than one cylinder.

Referring now to Fig. 2, which shows a working diagram of such a six-cylinder engine under the assumption that it is a four-cycle engine in which a complete cycle in each cylinder is per formed during two complete revolutions or '120 angular degrees of the crank shaft, the curves as represent the pressures in the individual cylinders of the engine. The numbers I to VI of the cylinders are indicated below the abscissae near the peaks of the corresponding pressure curves. Thus the diagram shows, for example, that the pressurefor cylinder m reaches a .u tac t-r at 3 about 150 angular degree position of the shaft. As pointed out above, fuel is injected in the cylinders by fuel feeders subject to the pressure in the cylinders. In a four-cycle the fuel supply then takes place during the air compression stroke in the cylinder, that is, shortly before the pressure in the cylinder reachw a maximum. The fuel supply to the cylinders is indicated in the diagram by crosshatched sur= faces 55. The fuel supply to cylinder m, for so example, takes place approximately between and angular degree positions of the crank shaft, whereas, the fuel supply to cylinder IV takes place between 330 and 380 degree can positions of the crank shaft. The compresion 45 or discharge stroke of all six pumps being driven by a common drive member takes place during the first degrees of the indicated cycle. The simultaneous fuel discharge periods of the pumps is illustrated by a single crosshatched surface 50 15c. As the diagram clearly brings out, the actuation of the feeder, that is, the supply of fuel from the feeder to the cylinder with respect to cylinders I and m, also takes place during the first 150 degree period of the cycle. Hence, g5

with an ordinary arrangement the fuel supplied by the pumps H) for cylinders I and III would have to overcome the pressure exerted on the fuel feeder by the air compression within said cylinders. As stated in the beginning, this could be done by the provision of stronger pumps, in the present instance with respect to cylinders I and III. According to our invention this is accomplished by the provision of special storing means l3 (Fig. 1) between the pumps l6 and the I fuel feeders l2 of the cylinders I and HI.

Referring now to Fig. 3, which shows more in detail the combustion cylinder I with its fuel metering pump l0, its feeder l2 and the storing means l3 between the feeder and the pump. The different elements of the engine are united by a casing I6. The cylinder I has a piston IT. Provided in a head l6 for the cylinder is an injection valve l9 having a valve member 20 biased in downward direction by a compression spring 2!. A lower portion 22 of the movable valve member 20 is reduced in diameter, forming a shoulder 23. The portion 22 and the valve casing form an annular chamber 24 connected to the fuel supply pipe 25. The supply of fuel under pressure by the pipe 25 to chamber 24 efiects upward movement of the valve member 20 against the biasing force of the spring 2! and permits the injection of fuel into the cylinder through a nozzle member 26. The other end of the pipe 25 is connected to the fuel feeder 12, which latter comprises a casing 21 and a differential piston 28. The reduced portion of the latter projects into a fuel chamber 29 and the lower portion of the differential piston projects into a chamber 30 and is biased in upward direction by a spring 3|. The chamber 30 communicates through a pipe 32 with the compression space of the cylinder. Thus the differential piston 28 is biased upward by the resultant force of the spring and the pressure in the combustion space. Assuming the chamber were filled with fuel, this fuel is forced through the pipe 25 and injected through the nozzle 26 into the cylinder during the air compression period of the cylinder. The injection stroke begins at a certain pressure in the cylinder and ends when the differential piston has reached a certain upper position.

The fuel pump [6 comprises a piston 33 having a lower block member 34 provided with a roller 35, which latter engages the drive member II, in

the present instance indicated as a cam 36 secured to a crank shaft 31 of the engine. The roller is held in engagement with the cam 36 by a biasing spring 38. The piston projects into a pump chamber 39 defined by the pump casing. Connected to this chamber is a discharge valve 40 biased towards closed position by a spring 4| and a combined inlet and relief valve 42 for connecting and disconnecting the compression space 39 with a fuel conduit 43. The suction and relief valve 42 includes a movable member 44 biased in downward direction by a spring 45 and adapted to be opened by a member 46 pivotally connected to a lever 41. The latter has a left-hand portion held on an adjustable eccentric 48 and alrighthand portion projecting into a slot 49 of the block member 34.

The operation of the pump is as follows: During downward movement of the 'pump piston 33 1 proved arrangement for combustion engines in a vacuum is created in the chamber 39, efiecting opening of the suction valve member 44 whereby fuel is supplied from the conduit 43 intothe chamber 39. As then the pump piston is forced upward, causing compresion of the fuel in the chamber 39, the valve member 44 is closed and at a certain pressure in the chamber 39 the discharge valve member 40 is opened, permitting the discharge of fuel through the discharge conduit 50. The flow of fuel from chamber 39 to conduit 50 is interrupted at a certain point by the opening of the valve member 44 acting then as a relief valve. The opening of this member is accomplished by the upward movement of the lever 41 which in a certain position causes the member 46 to force the movable member 44 upward whereby the pressure in the compression chamber 39 is relieved, the remaining fuel flowing back into the supply conduit 43 and permitting closing of the discharge valve 40. Connected between the pump, more particularly the discharge conduit 50 thereof, and the fuel feeder I2 is the fuel storing device l3. This device comprises a casing 5| forming a storing chamber 52 and having a piston 53 disposed within the chamber. The piston is biased in upward direction by a spring 54. The chamber 52 is connected to the fuel feeder l2 by the conduit 55 and a check valve 56, preventing backward flow and permitting the flow of fuel from the chamber 52 to the chamber 29 of the fuel feeder when the pressure in the chamber 52 is greater than the pressure in the chamber 29 of the fuel feeder. The check valve 56 is normally biased towards closing position by a spring 57. As pointed out above, such fuel storing device I3 is provided for each cylinder I and I11 with respect to which the fuel injection falls within the period of the fuel supply to the fuel feeders I2 by the corresponding pumps l0.

During operation the fuel compressed and dis- 95 charged by the pump l0 through the discharge conduit 50 is supplied to the chamber 52. The piston 53 of the storing device thereby is forced downward against the biasing force of'the spring 54. The check valve 56 remains closed because during this period it is subjected to the biasing force of the spring as well as the pressure in conduit 55, this pressure being high during this period due to the upward movement of the differential piston 28 of the fuel feeder. A short period of time after the termination of the fuel injection to cylinder I, the pressure in the cylinder decreases, causing a decreasing biasing force on the lower side of the differential piston 28 and permitting the latter to move downward, causing a reduced pressure in the chamber 29 of the fuel feeder. This reduced pressure permits opening of the check valve 56, the fuel contained in the storing chamber 52 then being forced into the feeder chamber 29 under the action of the spring biased piston 53. Thus, it will'be readily seen that the fuel supplied by the pump I0 is stored for a certain period of time in the storing device l3, whence it is supplied to the fuel feeder l2 after the termination of the fuel injection to 60 the cylinder I. The fuel supply arrangements for the cylinders I and III are alike and also the fuel supply arrangements for the cylinders II, IV, V and VT, respectively, the latter differing from the arrangements for cylinders I and III in that they do not include a storing device l3. In this case the discharge conduits 50 communicate directly with the chambers 29 of the corresponding fuel feeders 21, as indicated in Fig. 1.

With our invention we have provided an imwhich all cylinders are provided with like pump means and the fuel discharged from the pump means is stored at a comparatively low pressure in a storing device for certain cylinders The 7 arrangement may be such that the spring 54 of the storing device is so dimensioned that the piston 53 may be moved by a pressure of. 60 atmospheres, whereas 250 atmospheres are necessary to open the injection valve or nozzle 23. Hence the pump means has to be designed for 60 atmosphere pressure instead of for 250 lbs. pressure.

Having described the method of operation of our invention, together with the apparatus which we now consider to represent the best embodiment thereof, we desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. In a multi-cylinder internal combustion en-- gine, a plurality of engine cylinders, a fuel metering pump for each engine cylinder, the pumps being arranged to discharge fuel simultaneously, means associated with each engine cylinder for injecting the fuel discharged by the correspond ing fuel metering pump to said engine cylinder comprising a fuel feeder actuated by pressure variations in said engine cylinder and connected between said engine cylinder and said corresponding fuel metering pump, and a fuel storing device connected between the fuel feeder and the corresponding fuel metering pump of those engine cylinders whose fuel injection period falls within the period of fuel discharge from its fuel metering pump, whereby the discharge from said metering pump is stored in said storing device during the injection period and is forced into the feeder after the injection is terminated.

2. In a multi-cylinder internal combustion engine, a plurality of engine cylinders, fuel pumping means for the cylinders for compressing and discharging fuel during a definite period of a complete operating cycle of the engine, means associated with each cylinder for simultaneously receiving fuel from the pumping means and discharging the fuel to the corresponding engine cylinder, said means comprising a fuel feeder actuated by pressure variations in said engine cylinder and connected between said engine cylinder 5 tering pump for each engine cylinder, the pumps being arranged to discharge fuel simultaneously, means associated with each engine cylinder for injecting the fuel discharged by the correspond- 20 ing fuel metering pump to said engine cylinder comprising a fuel feeder actuated by pressure-variations in said engine cylinder and connected between said engine cylinder and said corresponding fuel metering pump, and a fuel storing device connected between the fuel feeder and the corresponding fuel metering pump of those engine cylinders whose fuel injection period falls within the period of fuel discharge from its fuel metering pump, whereby the discharge from said metering pump is stored in said storing device during the injection period and is forced into the feeder after the injection is terminated, the fuel storing device comprising a chamber communicatin with the pump, conduit means including a check 5 valve between the chamber and the feeder and a spring pressed piston for forcing fuel from the chamber into the feeder.

FRIEDRICH SASS. ERNST DAIBER. 

